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A Volcano May Be Growing Beneath Small New Zealand Town

Enough magma has gathered under the region to fill 80,000 olympic-sized swimming pools.

Underneath a small coastal town on New Zealand’s North Island, scientists have discovered a pool of magma building up, and it could be signaling the birth of a brand new volcano.

Scientists have been monitoring the region since the 1950s, and so far, enough magma has gathered under the region to fill 80,000 olympic-sized swimming pools. But this event did not capture the attention of geologists until the the town of Matata, home to 650 people, reported higher than usual earthquake activity over the past 10 years.

Geoscientists assumed this activity was due to tectonic plate activity, but after mapping the geological changes in the area using satellite radar and GPS over the past 60 years, the team showed that the earthquakes were likely caused by the magma stressing and breaking rock as it builds below the region. In fact, the accumulation of magma has pushed 154 square miles (400 square kilometers) of land up by 15 inches (40 centimeters).

The results were a surprise to the researchers because the town hasn’t had an active volcano nearby for at least 400,000 years. What’s more, the discovery is exciting for scientists because the town is just on the outskirts of the Taupo Volcanic Zone — one of the most active volcanic regions in the world that is spreading east to west at the rate of about 0.3 inches (8 millimeters) per year.

Below is an illustration of what the researchers believe is happening:

Looking south along the Taupo Volcanic Zone showing the subduction of the Pacific Plate under the North Island of New Zealand. Uplift suggests the presence of a magma beneath the Bay of Plenty coast at a depth of 6 miles. Photo credit: Ian Hamling

The team calculated that the magma pool is around 6 miles (9.5 kilometers) below the surface, so there isn’t a risk of an eruption any time soon. In fact, volcanoes take thousands of years to form, and sometimes they don’t turn into volcanoes at all. Rather, all the magma can cool and harden.

"Although the ultimate fate of the magma remains unclear, its presence may represent the birth of a new magma chamber on the margins of arguably the world’s most active region of silicic volcanism, which has witnessed 25 caldera-forming eruptions over the last 1.6 million years," the researchers wrote in Science Advances.

Although the researchers are confident with their results, there is room for error. More than half of the area they need to study is located under the ocean, which means they are unable to scan a good chunk of the surface level changes related to the pooling magma.

Nevertheless, the team hopes to use these data to not only understand more about how the volcano formation process works, but also to create better warning systems for magma-triggered earthquakes in the future.